Concrete bridge deck stresses induced by stay-in-place forms

In this study, the restraining actions induced by stay-in-place metal forms to concrete bridge decks are examined. A comparison between the behaviour of a concrete deck section constructed with regular stay-in-place metal forms and that constructed on a flat-bed geometry where the corrugations in the stay-in-place forms are filled with extruded polystyrene foam is conducted. Data consisting of three-dimensional concrete deck strains, thermal gradient profiles through the deck thickness, deck deflection profiles and reinforcement strains were recorded through a long-term sensory system consisting of 340 sensors embedded within the deck since construction. Analysis of stresses developed in the concrete deck material indicates that using the foam material to fill the corrugations proved to be successful in reducing the concrete shrinkage stresses at early age and also in reducing the constraining effects of the stay-in-place forms on deck expansion and contraction within the monitoring period of about 1 year.